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  1. /*
  2.  * 3GPP TS 26.245 Timed Text encoder
  3.  * Copyright (c) 2012  Philip Langdale <philipl@overt.org>
  4.  *
  5.  * This file is part of FFmpeg.
  6.  *
  7.  * FFmpeg is free software; you can redistribute it and/or
  8.  * modify it under the terms of the GNU Lesser General Public
  9.  * License as published by the Free Software Foundation; either
  10.  * version 2.1 of the License, or (at your option) any later version.
  11.  *
  12.  * FFmpeg is distributed in the hope that it will be useful,
  13.  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15.  * Lesser General Public License for more details.
  16.  *
  17.  * You should have received a copy of the GNU Lesser General Public
  18.  * License along with FFmpeg; if not, write to the Free Software
  19.  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20.  */
  21.  
  22. #include <stdarg.h>
  23. #include "avcodec.h"
  24. #include "libavutil/avassert.h"
  25. #include "libavutil/avstring.h"
  26. #include "libavutil/intreadwrite.h"
  27. #include "ass_split.h"
  28. #include "ass.h"
  29.  
  30. typedef struct {
  31.     ASSSplitContext *ass_ctx;
  32.     char buffer[2048];
  33.     char *ptr;
  34.     char *end;
  35. } MovTextContext;
  36.  
  37.  
  38. static av_cold int mov_text_encode_init(AVCodecContext *avctx)
  39. {
  40.     /*
  41.      * For now, we'll use a fixed default style. When we add styling
  42.      * support, this will be generated from the ASS style.
  43.      */
  44.     static uint8_t text_sample_entry[] = {
  45.         0x00, 0x00, 0x00, 0x00, // uint32_t displayFlags
  46.         0x01,                   // int8_t horizontal-justification
  47.         0xFF,                   // int8_t vertical-justification
  48.         0x00, 0x00, 0x00, 0x00, // uint8_t background-color-rgba[4]
  49.         // BoxRecord {
  50.         0x00, 0x00,             // int16_t top
  51.         0x00, 0x00,             // int16_t left
  52.         0x00, 0x00,             // int16_t bottom
  53.         0x00, 0x00,             // int16_t right
  54.         // };
  55.         // StyleRecord {
  56.         0x00, 0x00,             // uint16_t startChar
  57.         0x00, 0x00,             // uint16_t endChar
  58.         0x00, 0x01,             // uint16_t font-ID
  59.         0x00,                   // uint8_t face-style-flags
  60.         0x12,                   // uint8_t font-size
  61.         0xFF, 0xFF, 0xFF, 0xFF, // uint8_t text-color-rgba[4]
  62.         // };
  63.         // FontTableBox {
  64.         0x00, 0x00, 0x00, 0x12, // uint32_t size
  65.         'f', 't', 'a', 'b',     // uint8_t name[4]
  66.         0x00, 0x01,             // uint16_t entry-count
  67.         // FontRecord {
  68.         0x00, 0x01,             // uint16_t font-ID
  69.         0x05,                   // uint8_t font-name-length
  70.         'S', 'e', 'r', 'i', 'f',// uint8_t font[font-name-length]
  71.         // };
  72.         // };
  73.     };
  74.  
  75.     MovTextContext *s = avctx->priv_data;
  76.  
  77.     avctx->extradata_size = sizeof text_sample_entry;
  78.     avctx->extradata = av_mallocz(avctx->extradata_size);
  79.     if (!avctx->extradata)
  80.         return AVERROR(ENOMEM);
  81.  
  82.     memcpy(avctx->extradata, text_sample_entry, avctx->extradata_size);
  83.  
  84.     s->ass_ctx = ff_ass_split(avctx->subtitle_header);
  85.     return s->ass_ctx ? 0 : AVERROR_INVALIDDATA;
  86. }
  87.  
  88. static void mov_text_text_cb(void *priv, const char *text, int len)
  89. {
  90.     MovTextContext *s = priv;
  91.     av_assert0(s->end >= s->ptr);
  92.     av_strlcpy(s->ptr, text, FFMIN(s->end - s->ptr, len + 1));
  93.     s->ptr += FFMIN(s->end - s->ptr, len);
  94. }
  95.  
  96. static void mov_text_new_line_cb(void *priv, int forced)
  97. {
  98.     MovTextContext *s = priv;
  99.     av_assert0(s->end >= s->ptr);
  100.     av_strlcpy(s->ptr, "\n", FFMIN(s->end - s->ptr, 2));
  101.     if (s->end > s->ptr)
  102.         s->ptr++;
  103. }
  104.  
  105. static const ASSCodesCallbacks mov_text_callbacks = {
  106.     .text     = mov_text_text_cb,
  107.     .new_line = mov_text_new_line_cb,
  108. };
  109.  
  110. static int mov_text_encode_frame(AVCodecContext *avctx, unsigned char *buf,
  111.                                  int bufsize, const AVSubtitle *sub)
  112. {
  113.     MovTextContext *s = avctx->priv_data;
  114.     ASSDialog *dialog;
  115.     int i, len, num;
  116.  
  117.     s->ptr = s->buffer;
  118.     s->end = s->ptr + sizeof(s->buffer);
  119.  
  120.     for (i = 0; i < sub->num_rects; i++) {
  121.  
  122.         if (sub->rects[i]->type != SUBTITLE_ASS) {
  123.             av_log(avctx, AV_LOG_ERROR, "Only SUBTITLE_ASS type supported.\n");
  124.             return AVERROR(ENOSYS);
  125.         }
  126.  
  127.         dialog = ff_ass_split_dialog(s->ass_ctx, sub->rects[i]->ass, 0, &num);
  128.         for (; dialog && num--; dialog++) {
  129.             ff_ass_split_override_codes(&mov_text_callbacks, s, dialog->text);
  130.         }
  131.     }
  132.  
  133.     if (s->ptr == s->buffer)
  134.         return 0;
  135.  
  136.     AV_WB16(buf, strlen(s->buffer));
  137.     buf += 2;
  138.  
  139.     len = av_strlcpy(buf, s->buffer, bufsize - 2);
  140.  
  141.     if (len > bufsize-3) {
  142.         av_log(avctx, AV_LOG_ERROR, "Buffer too small for ASS event.\n");
  143.         return AVERROR(EINVAL);
  144.     }
  145.  
  146.     return len + 2;
  147. }
  148.  
  149. static int mov_text_encode_close(AVCodecContext *avctx)
  150. {
  151.     MovTextContext *s = avctx->priv_data;
  152.     ff_ass_split_free(s->ass_ctx);
  153.     return 0;
  154. }
  155.  
  156. AVCodec ff_movtext_encoder = {
  157.     .name           = "mov_text",
  158.     .long_name      = NULL_IF_CONFIG_SMALL("3GPP Timed Text subtitle"),
  159.     .type           = AVMEDIA_TYPE_SUBTITLE,
  160.     .id             = AV_CODEC_ID_MOV_TEXT,
  161.     .priv_data_size = sizeof(MovTextContext),
  162.     .init           = mov_text_encode_init,
  163.     .encode_sub     = mov_text_encode_frame,
  164.     .close          = mov_text_encode_close,
  165. };
  166.